appengine image API with GCS

gistfile1.go

import (
	"appengine/blobstore"
	aeimage "appengine/image"
)

func servingURL(c appengine.Context) error {
	blobKey, err := blobstore.BlobKeyForFile(c, "/gs/bucketname/file")
	if err != nil {
		return err
	}

	servingURL, err := aeimage.ServingURL(c, blobKey, &aeimage.ServingURLOptions{Secure: true})
	if err != nil {
		return err
	}
	c.Infof("servingURL: %s", servingURL.String())
	return nil
}